In the conventional manufacture of carpeting, tufted pile yarns or like facings are held in place by a primary backing, and typically a secondary backing—as well as possibly other layers—also associated with the carpeting. At least some of the carpet backings (particularly latex, EVA, PVC, or other polymer-based backings) use filler as an important component thereof. The standard filler that is used is a mineral filler, typically calcium carbonate, alone, or in combination with some other materials.
During the carpet manufacturing process there is waste carpeting produced, which is typically landfilled or burned. When new carpets are installed in place of old carpeting, the used, waste carpeting (which is post-consumer waste at that point) is ripped up and also typically landfilled or burned. The calcium carbonate, or like mineral fillers, that are used in carpet backings are mined, and therefore have associated therewith the conventional problems associated with the mining of materials. In certain waste carpeting materials, other materials, such as thermoplastic resins, form constituent parts of the waste material together with the calcium carbonate filler and are recoverable.
According to the present invention, methods of recycling waste carpeting, including calcium carbonate and thermoplastic resin materials, and carpeting produced utilizing such recycled materials, are provided which substantially eliminate or significantly reduce the problems discussed above. According to the present invention instead of using calcium carbonate, which is mined, as the filler for a carpet backing, recycled waste carpet containing calcium carbonate as well as a thermoplastic resin (from new carpet production and/or from post-consumer waste) is used as a filler material. The recycled material may also be used in conjunction with fresh calcium carbonate, e.g., freshly mined, as well as fresh thermoplastic resin. This substantially eliminates, or at least significantly reduces, the amount of landfilling or other waste disposal that is necessary for waste carpeting.
While the invention is particularly useful for recycling waste carpet in the manufacture of new carpeting, the invention is also applicable to the production of other materials containing fillers, including various extruded thermoplastic and thermoset materials that typically use calcium carbonate filler, including, but not limited to, roofing materials, road paving materials, awnings, and tarps.
According to one aspect of the present invention there is provided a method of recycling waste carpeting comprising substantially sequentially: (a) collecting waste carpeting; (b) processing the waste carpeting to provide a first material from the waste carpeting containing a filler and a thermoplastic resin; (c) adding the first material to a second material to provide a composite material useful in the manufacture of a useful product; and (d) making the useful product using the composite material.
In the method, step (a) may be practiced to collect substantially only post-consumer waste carpeting, substantially only waste carpeting from new carpeting manufacture, or a blend of both. Post-consumer waste carpeting can be cleaned by any conventional cleaning technique before use, if desired or necessary. While the method is typically practiced utilizing all of the face yarn and primary backing, and backcoatings, under some circumstances the method may further comprise, as part of step (b), separating the face yarn and primary backing from waste carpeting backcoating to produce a substantially face yarn and primary backing-free waste carpeting backcoating, and using substantially only the waste carpeting backcoating. Also, various carpet backcoatings may be separated from each other so as to use only one particular carpet backcoating, such as the primary or secondary backcoating.
The invention also as part of step (b) includes reducing the first material to a predetermined size in a range of 50–100 to 95–325 wherein the first number represents the percentage of the first material which will pass through a mesh screen having a mesh size corresponding to the second number. Also, step (c) may include adding the first material to the second material to form a carpet backcoating and step (d) is practiced by making a carpet backcoating. Additionally, the composite material of step (c) may be processed in molten form to have a viscosity in the range of 10,000 to 30,000 CPS. The latter viscosity range is particularly used for forming a primary backcoating for carpeting. In one embodiment of the useful product formed hereby, the carpet product may have a backcoating with about 3–30% EVA copolymer, about 32–45% resin and 50% filler wherein the filler comprises calcium carbonate and a predetermined percentage of the composite material.
In another embodiment hereof, the method may be practiced employing steps (a) and (b) above, and in lieu of steps (c) and (d), (c) heating the first material to a temperature enabling the first material to flow and (d) flowing the first material onto a second material to bond the first and second materials to one another to form a useful product. Thus, the waste carpet material when in flowable form may be placed for example on the backside of fiberglass carpet tile where the material bonds to itself and to the fiberglass when subjected to heat.
It will be appreciated that the method hereof is useful to form carpet backcoatings comprised of EVA or PVC or other polymer base backcoatings. The invention also further typically comprises making new carpeting with the carpet backcoating. Additionally, the method hereof is useful to form carpet backcoatings comprised of SBR latex compounds wherein the recycled calcium carbonate filler may be used in lieu of or in combination with fresh calcium carbonate to form the carpet backcoating in conjunction with other materials. Further, the composite material may be used to produce extruded thermoplastic or thermoset products.